1. Field of the Invention
The present invention relates to a disc brake assembly having a pair of brake shoes the friction pad members of which are pressed into contact with a disc rotor secured for rotation with a road wheel to apply a braking force to the road wheel.
2. Discussion of the Prior Art
In conventional disc brake assemblies, various counter-measures have been adapted to reduce brake noises caused by vibration of the disc rotor, brake shoes or the like. For example, Japanese Patent Laid-open Publication No. 3-79820 discloses a disc brake assembly in which the friction pad members of the brake shoes each are divided into two parts in a circumferential direction of the disc rotor to reduce brake noises. With the conventional countermeasures, however, the brake noises may not be sufficiently reduced.
Based on a theoretical analysis and experiments, the inventors have found the fact that the brake noises are caused by a vibration wave of three-nodes diametric mode, i.e. a vibration wave the one-wave length of which is one third (1/3) of a circumferential length of the disc rotor.